Bowling ball drilling

ABSTRACT

An apparatus for positioning a bowling ball during a drilling process and method that provides reproducible orientations of the ball for accurately modifying and repeating the drilling process is described. The apparatus affixed a bowling ball while exposing a sufficient portion of a surface of the ball where middle finger, ring finger and thumb holes are to be drilled. The apparatus positions the bowling ball for drilling holes of varying pitch without requiring the ball to be removed from its rigidly affixed position within the apparatus. Holes having severe pitches are easily drilled and reproduced, including oval holes having preselected oval rotations. A computer program converts inputted hand measurements to digitized apparatus movements for positioning the ball prior to drilling a desired hole. Digital encoders indicate apparatus movement that is matched with computer output for ease and repeatability in drilling a ball.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of application Ser. No. 08/129,750 filedSep. 30, 1993, now U.S. Pat. No. 5,427,478, for a "Bowling Ball DrillingApparatus".

BACKGROUND OF INVENTION

1. Field of Invention

The invention relates to an apparatus for positioning a bowling ballduring a drilling process and in particular to an apparatus and methodthat provides reproducible orientations of the ball for accuratelymodifying and repeating the drilling process.

2. Background Art

Bowling ball construction has become hi-tech over the last severalyears. Inner core designs generate varied amounts of hitting power,tailored tracking on a lane, and higher revolutions. Such ballimprovements have placed increased demand on properly fitting a bowlingball to a bowler. Most bowlers must pay a cost of losing several pinsdropped or frames lost every time they switch balls and acclimatethemselves to a different feel. This difference in feel make the bowlerreluctant to change balls even when a change is needed.

It is generally recognized by experienced bowlers that finger holes in abowling ball play a critical role in providing the bowler with a properfeel for holding and releasing the bowling ball in a consistent manner.The control that a bowler has over a bowling ball is dependent on theplacement, orientation, and cross-sectional configuration of the holesin the ball. As is generally the case in sports, a basic form is soughtand typically found but it is the process of repeating and continuing torepeat this form under the multitude of conditions presented duringcompetition, not least of which is achieving a feel that provides theconfidence to score well. The fit of the ball is always underconsideration.

It is also well known and accepted in the art of bowling ball drilling,that obtaining the basic measurements takes an experienced ball drillerand if such measurements were to be drilled by different experienceddrillers, the fit would be only similar. Variances and errors in bevelsize, drilling spans and pitches would vary. Technique varies even withexperienced drillers and typically it is a trial and error method thatultimately provides the bowler with a desired fit.

U.S. Pat. No. 3,263,531 discloses a bowling ball drill jig for drillingthumb and finger holes comprising a moveable apparatus for locating thecenter point of the hole to be drilled and selecting a desired plane forthe axis of the hole to be drilled. Calibration means is employed toaccount for hole edges. The patent teaches the importance of being ableto fix and hold the ball in a jig for greater drilling accuracy withouthaving to move or remove the ball from the jig after each hole isdrilled to allow proper measurement for drilling succeeding holes.

U.S. Pat. No. 3,521,506 discloses a method and apparatus for formingoblong holes of predetermined orientation in a bowling ball bysuperimposing a target with radial lines at predetermined angles, allradiating from a common center on a selected point on a line on theball. The line is rotated on the ball into coincidence with one of theradial lines, making a round hole in the ball. The ball is then moved apredetermined distance along one of the radial lines and additionalmaterial is removed from the side wall of the hole opposite thedirection of motion to make the hole oblong.

U.S. Pat. No. 3,095,767 discloses an apparatus and method for drillingholes in a bowling ball and reproducing the holes of a first bowlingball into a second bowling ball by positioning the first bowling ballinto a cradle, positioning inserts in each finger hole and providing aguide rod for establishing a locking position for tool holders. Theguide rod is removed; the second bowling ball is placed in position ofthe first; and holes drilled based on the guided selections.

In a manual for bowling pro shops and knowledgeable bowlers, "Fittingand Drilling a Bowling Ball" by Bill Taylor, the author points out theproblems in properly fitting a bowler for drilling a bowling ball andeven though it may be known what measurements are needed, accuratelyobtaining the measurements is not so simple. The author further pointsout that too many ill fitted balls result from inexperienced balldrillers. Twelve measurements are discussed for providing a proper fitwhich permits a proper swing and a proper release to maximize a bowler'schances for a satisfactory delivery. The author discloses methods formeasuring a bowlers hand and fingers for obtaining a set of measurementsthat can satisfy the bowler's needs. However, the author points out thatthough there are many talented ball drillers, most of them becometalented by trial and error and in doing so cause many problems in thecourse of their self education.

SUMMARY OF INVENTION

An apparatus for positioning a bowling ball for drilling thumb andfinger holes in the bowling ball comprises a frame having an aperturefor loosely receiving a bowling ball and means for rigidly affixing thebowling ball within the frame aperture for providing access to ahemisphere of the ball. Means are provided for rotating the frame, therotation having three degrees of freedom of rotational movement. Meansare also provided for communicating the rotating means with the frame.The apparatus further comprises means for mounting the apparatus to atable, the table having means for providing linear movement throughthree additional degrees of freedom.

In a preferred embodiment, the frame comprises a tube dimensioned tofreely receive the bowling ball, the tube having a top edge and a bottomedge. A top plate is affixed to the tube top edge. The top plate has anaperture for loosely receiving the bowling ball. A bottom plate isaffixed to the tube bottom edge. The bottom plate has an aperture forproviding access to the bowling ball affixed within the frame.

It is an object of the invention to provide a computer assisted drillingsystem that insures duplication of a desired fit ball. Each bowling ballis drilled using a method for drilling the bowling ball comprising thesteps of providing a frame for loosely receiving a bowling ball andrigidly affixing the bowling ball within the frame for exposing ahemisphere of the ball for drilling finger and thumb holes. Stepsfurther include selecting a drill bit sized to meet a predeterminedmeasurement and placing the bit in a chuck affixed proximate the framefor drilling the bowling ball. A reference point on the surface of thebowling ball is used for aligning the axis of the drill bit with thereference point. The frame is then rotated through a first arc about afirst axis through the center of the ball and through a second arc abouta second axis through the center of the ball. The rotating through thefirst and second arcs positions the drill bit above the surface of theball proximate a surface entry point for drilling a hole. The frame isdisplaced along the first axis for positioning the drill bit forproviding a hole having a lateral pitch and along the second axis forpositioning the drill bit for providing a vertical pitch. A hole isdrilled in the ball, the axis orientation of the hole resulting from theball rotating and displacing steps. The aligning of the drill bit isrepeated until a middle finger hole, a ring finger hole and a thumb holehave been drilled meeting a preselected set of measurements includingbridge and span distances and including hole sizes and hole axis lateraland vertical pitches.

In a preferred method for drilling finger and thumb holes, stepscomprise selecting a ball diameter, bridge and span measurements, thebridge measurement for defining a bridge surface distance between amiddle finger hole and a ring finger hole, a first span measurement fordefining a first span surface distance between a thumb hole and a middlefinger hole and a second span measurement for defining a second spansurface distance between a thumb hole and a ring finger hole. Diametersare selected for thumb and middle and ring finger holes. Lateral andvertical pitches are also selected for these holes. A drill bit sized toprovide the selected middle finger hole diameter measurements selected.The bit is placed in a chuck affixed proximate the frame for drillingthe bowling ball. The axis of the drill bit is aligned with a referencepoint on the ball. The frame is rotated for positioning the drill bitfor drilling a hole in the ball, the positioning for providing a middlefinger hole alignment having the selected middle finger lateral andvertical pitches. The frame is displaced for positioning the drill bitfor providing a middle finger hole in a position communicating the spanand bridge measurements and the middle finger hole is then drilled inthe ball.

The process continues for positioning and drilling the ring finger andthumb holes. The invention permits locating and rotating oval holes. Themethod steps further comprise selecting an oval hole dimension having aminor diameter and a major diameter and selecting a drill bit sized toprovide the minor diameter. An oval hole rotation can also be selected.The frame is rotated and displaced for positioning the drill bit fordrilling a first hole having an axis corresponding to the axis of theoval. The first hole is drilled. The frame is then rotated and displacedfor drilling a second hole, a portion of the second hole comprising aportion of the first hole, wherein the axis of the second hole ispositioned for providing a second oval hole having the oval holerotation. The frame is again rotated and displaced for drilling a thirdhole, a portion of the third hole comprising a portion of the firsthole, wherein the axis of the third hole is positioned for providing theoval having the selected oval rotation, minor and major diameters.

In the preferred embodiment of the invention, computer aided controlsare provided. The method further comprises operating a computer fordetermining rotation and displacement of the frame. The computerperforms the steps of receiving thumb and finger hole measurementscomprising hole diameter, lateral pitch, vertical pitch, bridge and spandistances, oval dimensions, and ball diameter. An algorithm thenconverts the hole measurements to frame rotational and linear movementsfor orienting a drill bit over a portion of the bowling ball fordrilling a selected hole having the received ball diameter. Thealgorithm digitizes the rotational and linear frame movements withrespect to the reference point, for use in directing an operator inmoving the frame. In the preferred embodiment, digital encoderscommunicating with the frame provide digitized readings responding toframe rotational and displacement movements. The frame is rotated untilan encoder rotational value corresponding to a calculated computerdigital value for the computer digitized movements is reached. Likewise,the frame is displaced until an encoder displacement value correspondingto a calculated computer digital value for the computer digitizedmovement is reached.

It is an object of the invention to provide a fixture and method forrigidly holding a bowling ball during the drilling process that hasthree rotational degrees of freedom while permitting access to a bowlingball hemisphere, the fixture securely positioning the bowling ball at apoint of reference.

It is a further object of the invention to provide a method forprecisely drilling and reproducing the precision drilling of a bowlingball to other balls by one having little skill in the art of drillingballs by repeating drilling steps. The drilling is to include a widerange of pitches not available from prior art devises and methods. Inaddition, it is an object to provide oval holes for thumbs and fingersat selected oval angles, and reproducing the oval angles for selectedmajor and minor oval dimensions.

It is yet another object of the invention to provide a method for usingfinger measurements and providing rotational and linear measuredmovements of a bowling ball for drilling the ball. Further, it is anobject to vary one measurement while fixing remaining measurements, suchvariation to provide a quantification of feel that can be incrementallyadjusted.

BRIEF DESCRIPTION OF DRAWINGS

A preferred embodiment of the invention as well as alternate embodimentsare described by way of example with reference to the accompanyingdrawings in which:

FIG. 1a is a front view of an apparatus used in the preferred embodimentof the invention illustrating a bowling ball affixed within theapparatus;

FIG. 1b is a cross-sectional view of the O-ring and ball;

FIG. 1c shows the O-ring seated in the cradle;

FIG. 2a is a perspective view of a bowling ball having three holes;

FIG. 2b is a cross-sectional view of a bowling ball illustrating across-sectional plane comprising a finger hole and a thumb hole;

FIG. 2c is a cross-sectional view of a bowling ball illustrating across-sectional plane comprising a middle finger hole and a ring fingerhole;

FIG. 3a is a partial functional view of a bowling ball illustratingrotational movement and displacement;

FIG. 3b through 3f are varying positional views of FIG. 3a illustratingfive degrees of movement;

FIG. 4 is a side view of the apparatus used in the preferred embodimentand shown in FIG. 1;

FIGS. 5a through 5d illustrate a well known method of drilling a holeinto a bowling ball wherein the hole is to have a predetermined pitch;

FIGS. 6a through 6c illustrate a prior art hole drilling method forproviding pitch to a hole to be drilled into the ball;

FIG. 7 is a partial cross-section of a bowling ball illustrating apreferred method of the invention for accurately determining theorientation of a drill bit for drilling a hole having a desired pitch;

FIG. 8A and 8B comprise a chart diagramming the steps in a samplecalculation of frame and table movements required to provide holeshaving a desired pitch;

FIG. 9 is a flow chart diagramming a process for drilling holes in abowling ball using the preferred embodiment of the invention; and

FIG. 10 is a sample computer output illustrating the format provided inthe preferred embodiment of the invention for use in providing themethod steps of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

A preferred embodiment of the invention is illustrated in FIG. 1 whereinan apparatus 10 for rigidly holding a bowling ball 12 and for orientingthe bowling ball 12 through various angles of rotation is described. Theapparatus 10 comprises a frame 14 formed by a rigid cylindrical tube 16.To improve rigidity, a top plate 18 is affixed along a top edge 20 and abottom plate 22 is affixed along a bottom edge 24 of the tube 16. Theframe 14 takes on a circular form with a cross-section having an I-beamshape in the preferred embodiment. A vise 26 is affixed to the frame 14.The vice 26 comprises a fixed cradle 28 having a concave surface 30 forreceiving the bowling ball 12. The vise 26 further comprises a keyedcradle 32 opposing the fixed cradle 28. The keyed cradle also has aconcave surface 34 for receiving the bowling ball 12 and in combinationwith the keyed surface affixes the bowling ball 12 in a position whereina hemisphere 36 of the bowling ball 12 lies above the top plate 18within a top plate aperture 19 and permits access to a substantialportion of the hemisphere 36 for purposes of drilling holes into theball 12. A bottom plate aperture 23 permits the ball 12 to passtherethrough and permits access to the ball 12 for holding the ball 12in position while affixing the ball 12 within the frame 14. The vice 26has a handle 38 for driving a screw assembly (not shown) for biasing theball 12 between the keyed cradle 32 and the fixed cradle 28. In thepreferred embodiment, the fixed cradle concave surface 30 has a rubberO-ring 31 affixed within an O-ring groove 33 typically used to positionan O-ring for enhancing friction between the ball 12 and the surface 30for further preventing rotation of the ball 12 during a drilling step.The keyed cradle 32 comprises a key way and key assembly (not shown) forcausing the keyed cradle 32 to move toward the ball 12 without rotationof the keyed cradle 32 and for enhancing the rigidity with which thevice 26 holds the ball 12 in a fixed position within the frame 14.

To further establish an understanding of the need for the invention, abrief discussion of terms describing the holes typically formed withinthe bowling ball 12 is in order. With reference to FIG. 2a, the bowlingball 12 may comprise two holes but will typically comprises three, athumb hole 40, a middle finger hole 42, and a ring finger hole 44. Abridge 46 separates the finger holes 42 and 44. A middle finger span 48and ring finger span 50 respectively separate the middle finger hole 42and the ring finger hole 44 from the thumb hole 40. As is usually thecase, a reference point 52 is placed on the ball surface 54 for use as aguide in positioning the holes.

Each hole 40, 42, and 44, will be drilled using an appropriate drill bitto form the hole diameter required. In the preferred embodiment, theball 12 is maneuvered with respect to the bit for drilling a hole havinga specific pitch. Pitch, although well known as a term of art is notnecessarily well known as to what it describes as is pointed out in thereference manual discussed in the background section of thisspecification. To emphasize by way of example and to further show a needaddressed by the invention, consider the cross-sectional views of thebowling ball 12 as illustrated in FIGS. 2b and 2c. By way of example, ifa hole 44 is drilled into the ball 12, and an axis 56 of the hole 44passes through a ball center 58, the hole 44 is said to have a zeropitch. A closest distance between the ball center 58 and the hole axis56 is zero.

With reference to FIG. 2b, showing a cross-section of the ball 12wherein a cross-sectional plane 60 comprises a finger hole 44 and athumb hole 40, a relationship between axes of fingers and thumbdescribes forward and reverse pitch. A distance between the ball center58 and a finger hole axis 56a when the axis 56a is in a direction awayfrom the thumb hole 40 is a reverse finger pitch 62. A distance betweenthe ball center 58 and an axis 56b when the axis 56b is in a directiontoward the thumb hole 40 is a forward finger pitch 64. With reference tothe finger hole 44, the reverse thumb pitch 66 and the forward thumbpitch 68 are thus described.

Holes will also be described as having a left lateral pitch and a rightlateral pitch. With reference to FIG. 2c, a cross-sectional plane 70through the ball center 58 comprises the finger holes 42 and 44. For themiddle finger 42 having an axis 72, a distance an axis 72a is away fromthe center 58 and to the left or away from the ring finger hole 44 is alateral left pitch 74. A distance an axis 72b is away from the center 58and to the right or toward the ring finger hole 44 is a lateral rightpitch 76. Left and right distances from the center 58 for axes of thering finger hole 44 and thumb hole 40 will likewise define lateral rightand left pitches for these holes as well.

In the preferred embodiment of the invention, the bowling ball 12remains affixed within the frame 14 of the apparatus 10 and the frame 14is maneuvered for drilling holes having varying pitches, angles andshapes. By way of example, and as illustrated in FIG. 3, the followingterminology is adopted for describing the movements:

                  TABLE 1                                                         ______________________________________                                        MOVEMENT DEFINED                                                              MOVEMENT   ELEMENT MOVED  TYPE MOVEMENT                                       ______________________________________                                        initialize Reference Point 52                                                                           align bit 78                                        Up - Down  Drill Bit 78   Lateral (z-axis 92)                                 Left - Right                                                                             Table 98       Horizontal (x-axis 90)                              Forward - Back                                                                           Table 98       Horizontal (y-axis 82)                              Tilt       Frame 14       x-axis rotation 86                                  Turn       Frame 14       y-axis rotation 84                                  Spin       Frame 14       z-axis rotation 88                                  ______________________________________                                    

As is illustrated in FIG. 3, a drill bit 78 is affixed within a chuck 80of a drill (not shown) and aligned above the ball reference point 52 forestablishing a initial position. The ball 12 is then laterally displacedand rotated to position the ball 12 with respect to the bit 78 forallowing the bit 78 to be directed along its axis for drilling aprescribed hole in the ball 12. As illustrated in FIG. 3a, the ball 12is rotated about a y-axis 82 through a y-axis of rotation 84 asillustrated by the arrow of FIG. 2a. As described earlier and by way ofexample, a thumb hole 40 is drilled and will have a zero pitch if itsaxis passes through the ball center 58. To drill a second hole, the ball12 will be rotated back to the reference 52 by reversing the rotation 84where the bit 78 can be changed for drilling the next hole. An x-axisrotation 86 as illustrated in FIG. 3c positions the bit 78 over the ballsurface 54 for drilling a second hole, which in our example will be themiddle finger hole 42. The ring finger hole 50 is then readied forposition by rotating the ball about a z-axis of rotation 88, asillustrated in FIG. 3c, being reminded that simple rotating the ball 12without repositioning the ball center 58 thus having all hole axespassing through the center 58 results in holes having zero pitch. Toprovide pitch to any hole, a displacement of the ball center 58 isrequired. Depending on the pitch desired, the frame 14 and thus the ballis displaced along the y-axis 82 an x-axis 90 to provide the forward orreverse and left or right pitch desired as illustrated in FIGS. 3e and3f. In the preferred embodiment, movement along a z-axis 92 is completedby advancing the rotating drill bit 78 toward and away from the ball 12.

In the preferred embodiment of the invention, the bit 78 used is aspiral-fluted indexable drill having heavy duty inserts for increasedaccuracy and feed rates. The bit 78 comprises a side cutting edge forproviding milling capability unlike a standard drill which will driftwhen entering a round surface such as a bowling ball 12 or when boring ahole side when providing oval shaped holes.

Typically in the art, a bowling ball to be drilled will have to berepositioned within its clamping device in order to provide the range ofhole shapes, angles and pitches requested by a bowler. Some devices asdiscussed in the background section of this specification will hold theball clamped through many drilling steps but are somewhat limitedespecially for the combination of holes requested by a skilled andprofessional bowler. Repeating a set of measurements or modifying onemeasurement while repeating the balance of measurements is then anobject of the invention. Once the ball 12 has been affixed within theframe 14 as described, it need not be removed until the drilling stepsare completed. Again with reference to FIG. 1, to accomplish this, theapparatus 10 further comprises three revolving platforms.

Rotation about the z-axis 88 is accomplished using a rotational device94 having a base 96 rigidly affixed to a table 98. In the preferredembodiment, the table 98 is that of a milling machine (not shown)wherein the milling machine comprises means for table displacement alongthe x-axis 90 and y-axis 82. The platform base 96 is rotatably affixedto a revolving platform 100. The platform 100 is rotated using a handle102 which drives rotating gears (not shown) causing z-axis rotation 88of the platform 100 referred to in this specification as spinning. Thedegree of spin is measured by an index 97 placed on the base 96 movedalong a scale 99 placed on the revolving platform 100 communicating withthe index 97. The z-axis platform 100 is rigidly affixed to a bracket104 as shown in FIG. 4 illustrating a side view of the apparatus 10. Thebracket 104 comprises an L-shaped cross-section wherein one leg of thebracket 104 is affixed to the z-axis platform 100 and the other leg ofthe bracket 104 is affixed to a y-axis rotational device 106 placing they-axis rotational device 106 at a right angle to the z-axis rotationaldevice 94. As with the z-axis device 94, the y-axis device 106 has arevolving platform 108 rotatably affixed to a base 110 along with ahandle 112 communicating with gears for rotating the platform 108. Thisy-axis base 110 is rigidly affixed to the bracket 104. As discussed, anindex 109 communicates with a scale 111 for measuring a turn asdescribed in this specification. The y-axis revolving platform 108 isrigidly affixed to a second L-shaped bracket 112 on one leg of thebracket 112. The other leg is rigidly affixed in a similar manner asherein described to an x-axis rotational device 114. The x-axisrotational device 114 is rigidly affixed at a right angle to the y-axisdevice 106. As in the devices 94 and 106, the x-axis revolving device114 comprises a base 116 rigidly affixed to the second L-shaped bracket112 and a revolving platform 118 rotatably affixed to the base 116.Again, as with the z-axis device 94, the x-axis device 114 has a handle113 communicating with gears for rotating the platform 180. An index 117communicates with a scale 119 for measuring a tilt as described in thisspecification and as illustrated in FIG. 1. Again with reference to FIG.1, the vise 26 is affixed to the x-axis device 114. With the arrangementof the devices 94, 106, and 114, z-axis rotation 88, y-axis rotation 84and x-axis rotation 86 are achieved.

In the preferred embodiment of the invention, the apparatus 10 providesthe rotational movements, rotation about the x-axis or tilt, rotationabout the y-axis or turn, and rotation about the z-axis, spin asdiscussed. The table 98 of the mulling machine provides movement alongthe x-axis 90 or left and right, and movement along the y-axis 82 orforward and back. The drill bit moves along the z-axis 92 or up anddown.

Software includes trigonometric algorithms that convert the geometry ofthe holes 40, 42, and 44 to digitized movements of the ball 12 fordrilling steps to meet predetermined hand measurements. A workerpositions the ball 12 within the frame 14 as herein described and alignsthe drill bit 78 over the ball reference point 52. Computer outputprovides digital movements for each hole to be drilled. In the preferredembodiment, digital encoders are affixed to the frame 14 and table 98rotating and displacement controls for providing a readout from theencoder that matches the digital output from the computer output. In thepreferred embodiment, input to the computer comprises bowler handmeasurements comprising Ring Finger, Middle Finger, and Thumb Diameters,Lateral Pitch (Left or Right), and Forward or Reverse Pitch. Inaddition, the Bridge 46, Middle Finger to Thumb Span 48, Ring Finger toThumb Span 50 distances and whether the bowler uses his right hand orleft hand are provided as computer input. The computer provides x-axisrotation 86 and y-axis rotation 84, and x-axis 90 and y-axis 82displacement movements necessary to provide middle finger 42, ringfinger 44 and thumb 40 holes having proper pitch and position relativeto the ball reference point 52 in a digitized format for matching with aformat for an output of the digital encoders.

Calculations include positioning holes and providing pitches to eachhole as desired. To better appreciate the invention, first consider aknown bowling ball drilling method, as illustrated in FIG. 5a through5d. With reference to FIG. 5a, a bowling ball is clamped in a cradle(not shown) wherein a drill bit 78 affixed within a chuck is alignedwith the reference point 52 typically affixed to the ball surface by aball manufacturer. The cradle is configured such that the ball 12 may berotated about the ball center 58 by releasing the clamped ball andmanually rotating the ball 12 for positioning the bit 78 above a markedposition 53 for drilling a desired hole, as illustrated in FIG. 5b. Ifthe hole to be drilled is to have a pitch, for example a left lateralpitch 74, the clamp is displaced by the amount of the pitch 74 requestedas illustrated in FIG. 5c. The ball 12 is then released from the clampand rotated until the bit 78 is positioned above the marked holeposition 53 as illustrated in FIG. 5d. A template is typically used formarking finger and thumb locations on the ball surface. The ball 12 isagain clamped and a hole is drilled. In another known method asdescribed earlier in the Background section of this specification, aball 12 is clamped and the bit 78 is aligned over the ball referencepoint 52 as is illustrated in FIG. 6a. The ball 12 is rotated whileremaining affixed within a fixture (not shown) until the bit 78 ispositioned above the designated location 53 as is illustrated in FIG.6b. To provide a left lateral pitch 74, the bit 78 is rotated usingpredetermined indicator marking on the fixture as illustrated in FIG.6c. Error is introduced whenever a ball 12 is released from its fixedposition. Although known and unwanted, this error has been acceptedwithin the art. In addition, displacing the ball 12 to provide a pitch74 and rotating the ball 12 to then account for a proper hole location53 on the surface of the ball without accounting for ball movementsintroduces even more error. For the prior art, correcting for this errorhas not been addressed.

The invention herein described provides the apparatus 10 and the methodthrough its computer calculations to avoid such error. By way of exampleand with reference to FIG. 7, consider a desired thumb hole 40 having areverse pitch 68 as is typically requested by a bowler. In the priorart, the ball 12 would be rotated about its center 58 or point "O" asillustrated in FIG. 7, to a marked template point "A" where the hole 40is to be drilled. The ball would then be displaced by a distance equalto the required pitch 68 and then rotated again until the point "A" isaligned with the bit as described earlier. Error is introduced when theball 12 is rotated about its center 58 as has been the case in the priorart. This error is avoided in the invention being described herein.

By way of example, consider drilling a thumb hole having a reversepitch. Again with reference to FIG. 7, based on input data describedearlier, calculations are first made in a plane 59 passing through theball center 58 that includes the hole center 53 on the ball surface 54also indicated by point "A" in FIG. 7. Such a plane 59 is thecross-sectional view illustrated in FIG. 7. If there were to be no leftor right lateral pitch, the axis of the hole would lie in this plane 59.A half arc distance between the thumb hole 40 and a finger hole iscalculated and a point "E" is determined from which further calculationsare to be made. Point "E" represents a half span point in thecalculation. Distance AE is thus determined. A point "D" is determinedwhere a line passing through the ball center 58 (point "O") and "D" isparallel to the desired axis of the thumb hole 40 to be drilled. Thenext step in the calculation is to determine a Distance OC that the ballis to be displaced in order to align a drill bit (not shown in FIG. 7)in a position to bore out the desired hole.

Distance AO is the ball radius and its dimension calculated from themeasured diameter. OB is known for it represents the desired reversepitch 68. By definition of pitch, it is known that OB is perpendicularto OA. Triangle AOB is a right triangle. Distance OC is being sought andis the actual displacement of the ball center 58. Angle OCA is thereforea right angle and Triangle OCB a right triangle. From Triangle AOB,Angle OBA is determined. In Triangle OCB, Distance OC is thendetermined. The ball 12 is thus rotated from the half span point "E" topoint "D" and then displaced by a Distance OC to provide the properdesired pitch.

In an example of measurements and drilling procedures, it has been foundthat a 0.50 inch pitch requires a 0.496 inch displacement. A four inchpitch requires only about a three inch displacement. In addition,accounting for ball diameter in the calculations has shown that the balldiameter variations permitted by the manufacturers and allowed bybowling authorities can result in approximately a one sixteenth incherror when comparing a permitted diameter of 8.595 inches to a permitteddiameter of 8.500 inches for a typical four inch to five inch span. Suchan error is easily felt by the bowler.

In the above thumb hole 40 example, if there was to be a requirement forthe thumb hole 40 to have a left or right lateral pitch as well as thereverse pitch 68 illustrated, similar calculations would be made in asecond plane. The second plane would be perpendicular to the plane 59 ofFIG. 7 and include the point "A". Similar calculations are thencompleted for each hole. In the preferred embodiment of the invention,calculations are made using well known spread sheet packaged softwarehaving formula translation capability. A sample software calculation ispresented in the chart of FIG. 8 where the calculation is completed fora right handed bowler having the "given information" presented in thechart.

In the total drilling procedure, and with reference to FIG. 8, abowler's hand is measured using known skills 115. The ball 12 is weighedand an axis passing through ball center 58 is identified by marking theball 116. The ball diameter is measured 117 and the measured dataentered into the computer 118. A computer printout 119 is provided. Asample printout is illustrated in FIG. 10 wherein rotational 120 andlinear 122 movements are displayed. These movements 120 and 122correspond to the movements of the frame 14 and table 98 describedearlier in this detailed description. As illustrated in FIG. 10,movements for the middle finger, ring finger and thumb are provided. Thecalculated movements are matched 124 with the frame 14 and table 98movements displayed on the digital encoders making it a drilling processthat requires little experience to perform and thus meets an objectiveof the invention as described.

If an oval hole is to be drilled, the milling drill bit describedearlier is used in order to eliminate tapering of the hole asexperienced when using conventional drill bits that cut only at bottomcenter of the bit. The milling drilling tool insures parallel successiveenlargements of the original hole to create a true oval with regards topitch and size due to its side cutting ability. In the situation wherethe oval hole is to be rotated about the z-axis 88, the hole is drilledprior to rotation. The z-axis 88 is then rotated to the desired angleand the drill is then moved utilizing the tables X and Y axis until thedrill milling tool moves freely into and out of the original circularhole. The precision of the frame 12 and table 98 movements is reliedupon to preserve accuracy especially since the digital displays remainin tack identifying precise positioning. The cutting tool bit is thenindexed along a major oval axis both sides of center to form therequired oval.

In the foregoing description, certain terms have been used for brevity,clearness and understanding, but no unnecessary limitations are to beimplied therefrom beyond the requirements of the prior art. Such termsare used for descriptive purposes herein and are intended to be broadlyconstrued. Moreover, the embodiment of the apparatus illustrated andmethod of use described herein are by way of example, and the scope ofthe invention is not limited to the exact details disclosed.

While a specific embodiment of the invention has been described indetail herein above, it is to be understood that various modificationsmay be made from the specific details described herein above withoutdeparting from the spirit and scope of the invention as set forth in theappended claims.

What is claimed is:
 1. A method for drilling holes in a bowling ball,the holes having a predetermined pitch, the drilling method comprisingthe steps of:providing a frame for receiving a bowling ball; rigidlyaffixing the bowling ball within the frame; exposing a substantialportion of the ball for drilling finger and thumb holes; selecting a bitsized for drilling a hole having a predetermined dimension; placing thebit in a chuck affixed proximate the frame for drilling the bowlingball; selecting a reference point on the surface of the bowling ball;aligning the axis of the bit with the reference point, wherein a lineextending through the axis passes through the ball center; rotating theframe through a first arc about a first axis, an extension of the firstaxis passing through the ball center; rotating the frame through asecond arc about a second axis, an extension of the second axis passingthrough the ball center, the rotating through the first and second arcsfor positioning the bit in an orientation parallel to a hole to bedrilled; displacing the frame a predetermined distance for positioningthe bit for providing a hole having a desired lateral pitch; displacingthe frame a predetermined second distance for positioning the bit forproviding a desired vertical pitch; and drilling a hole in the ball, theaxis orientation of the hole resulting from the ball rotating anddisplacing steps for providing desired lateral pitch and vertical pitch.2. The method as recited in claim 1, further comprising the stepsof:selecting a ball diameter; selecting a bridge measurement, the bridgemeasurement for defining a bridge surface distance between a middlefinger hole and a ring finger hole; selecting a first span measurement,the first span measurement for defining a first span surface distancebetween a thumb hole and a middle finger hole; selecting a second spanmeasurement, the second span measurement for defining a second spansurface distance between a thumb hole and a ring finger hole; selectinga middle finger hole diameter; selecting a middle finger lateral pitch;selecting a middle finger vertical pitch; selecting a bit sized toprovide the selected middle finger hole diameter measurement; placingthe middle finger sized bit in a chuck affixed proximate the frame fordrilling the bowling ball; aligning the axis of the middle finger bitwith the reference point; rotating the frame for positioning the middlefinger bit for drilling a hole in the ball, the positioning forproviding a middle finger hole alignment having the selected middlefinger lateral and vertical pitches; displacing the frame forpositioning the bit for providing a middle finger hole in a positioncommunicating the span and bridge measurements; drilling a middle fingerhole in the ball; selecting a ring finger hole diameter; selecting aring finger lateral pitch; selecting a ring finger vertical pitch;selecting a drill bit sized to provide the selected ring finger holediameter measurement; placing the ring finger sized bit in a chuckaffixed proximate the frame for drilling the bowling ball; aligning theaxis of the ring finger bit with the reference point; rotating the framefor positioning the ring finger bit for drilling a hole in the ball, thepositioning for providing a ring finger hole alignment having theselected ring finger lateral and vertical pitches; displacing the framefor positioning the ring finger bit for providing a ring finger hole ina position communicating the span and bridge measurements; drilling aring finger hole in the ball; selecting a thumb hole diameter; selectinga thumb hole lateral pitch; selecting a thumb hole vertical pitch;selecting a drill bit sized to provide the selected thumb hole diametermeasurement; placing the thumb hole sized bit in a chuck affixedproximate the frame for drilling the bowling ball; aligning the axis ofthe thumb hole sized bit with the reference point; rotating the framefor positioning the thumb hole drill bit for drilling a thumb hole inthe ball, the positioning for providing a thumb hole alignment havingthe selected middle finger lateral and vertical pitches; displacing theframe for positioning the thumb hole drill bit for providing a thumbhole in a position communicating the span measurements; and drilling athumb hole in the ball.
 3. The method as recited in claim 2, furthercomprising the steps of:selecting an oval hole dimension having a minordiameter and a major diameter; selecting a bit for drilling and milling,the bit sized to provide the minor diameter; selecting an oval holerotation; rotating and displacing the frame for positioning the bit fordrilling a first hole having an axis corresponding to the axis of theoval; drilling a first hole; rotating and displacing the frame formilling a second hole, a portion of the second hole comprising a portionof the first hole, wherein the axis of the second hole is positioned forproviding a second oval hole having the oval hole rotational; androtating and displacing the frame for milling a third hole, a portion ofthe third hole comprising a portion of the first hole, wherein the axisof the third hole is positioned for providing the oval hole having theselected oval rotation, minor and major diameters.
 4. The method asrecited in claim 2 comprising a computer having a software program forcalculating rotation and displacement of the frame, the computerperforming the steps of:receiving thumb and finger hole measurementscomprising hole diameter, lateral pitch, vertical pitch, bridge and spandistances, oval dimensions, and ball diameter; converting the holemeasurements to frame rotational and linear movements for orienting adrill bit over a portion of the bowling ball for drilling a selectedhole having the received ball diameter; and digitizing the rotationaland linear frame movements with respect to the reference point, thedigitizing useful in directing an operator for moving the frame.
 5. Themethod as recited in claim 4, further comprising the steps of:affixingrotary encoders to the frame for providing digitized readings respondingto frame rotational and displacement movements; rotating the frame forproviding an encoder rotational value corresponding to a calculatedcomputer digital value for the computer digitized movements desired; anddisplacing the frame for providing an encoder displacement valuecorresponding to a calculated computer digital value for the computerdigitized movement desired.
 6. The method as recited in claim 4, furthercomprising the steps of:determining an angle of rotation for aligningthe bit parallel to a desired axis of a hole to be drilled, an axisextension of the bit passing through the ball center; rotating the framefor placing the bit in an orientation for drilling a hole parallel to adesired hole; determining a displacement for the frame for placing thebit coincident with an axis of a hole to be drilled, the hole having adesired pitch; and displacing the frame such that the ball is in aposition for drilling a hole.
 7. The method as recited in claim 4,further comprising the steps of:determining a first plane having theball center and an axis of a desired hole to be drilled; determining anangle of rotation within the first plane for aligning the bit parallelto a desired axis of a hole to be drilled, an axis extension of the bitpassing through the ball center; rotating the frame for placing the bitin an orientation for drilling a hole parallel to a desired hole;determining a displacement within the first plane for displacing theframe for placing the bit coincident with an axis of a hole to bedrilled, the hole having a desired pitch as measured within the firstplane; displacing the frame such that the ball is in a position fordrilling a hole; determining a second plane having the axis of thedesired hole to be drilled; determining an angle of rotation within thesecond plane for aligning the bit parallel to the desired axis of thehole to be drilled, an axis extension of the bit passing through a pointon the second plane formed by an intersection of a line passing throughthe ball center and the second plane, the line perpendicular to thesecond plane; rotating the frame for placing the bit in an orientationfor drilling a hole parallel to the desired hole; determining adisplacement within the second plane for displacing the frame forplacing the bit coincident with the axis of the hole to be drilled, thehole having a desired pitch as measured within the first and secondplanes; displacing the frame such that the ball is in a position fordrilling the desired hole; and drilling the desired hole.